LowSS

I'm getting a thumping noise under hard acceleration, sounds like its coming from the rear of the car, only in 1st gear. I just changed the tranny mount today, didnt make a difference, torque arm mount looks good, everything seems tight. Only thing I can find odd is that theres a mark on the axle where the intermediate pipe is hitting it under acceleration. I checked the bumpstops and there not cracked but they look a little wore, then again, I'm not sure how there supposed to look. Only other place I can see the exhaust touching is the driver-side collector is touch the heat shield. Car has the Eibach Pro-kit with Edelbrock shocks, anything else I can check out? Thanks in advance.

pat


'00 NBM SS A4
Pacesetter Headers, ORY, Lid, Eibach Pro-kit

Shooter_Jay

when I bought mine it did that, tunred out that the borla cat-back was bumping the floor under hard acceleration. I loosed up the exhaust pipe clamps, repositioned the offending pipe so it was further away from the floor. It never hits now.

jimmyblue

iTrader: (11)

If it's following wheel speed check that the I-pipe isn't
interfering with the driveshaft balance weight or yoke;
they can run pretty close.

LowSS

I didnt see any marks on the I-pipe or driveshaft but i'll take a closer look. I originally said it was coming from the rear, but the more I hear it, the more I think its more towards the front, can feel something banging driverside under my feet. Thanks for the help.

pat

gordz32

Check ur u-joints on the driveshaft, try and twist the driveshaft and see if it moves when its in park.

MdFormula350

iTrader: (4)

the drivers side lifts up and something hits the floorpan it seems, make sure you have decent clearance where the header is at near the floorpan as well as the y-pipe. sounds like your stock engine mounts have alot of play and things are moving too much. check those out.

BadMonkey

iTrader: (1)

My old 2000 Z28 did that as well. Turned out to be the Y Pipe from the headers. When the engine torqued over under hard excelleration the y pipe would slam under the driverside floor pan, drove me nuts. On another note look to see if your spare tire is loose

ZFan88

iTrader: (4)

Check the y-pipe...and also check the two main torque arm bolts to make sure they're tight

gun5l1ng3r

What is happening if I get a large thump only when accelerating over bumps (bigger bumps)? Maybe the axle hitting the rear hump?

chupr0kabra

iTrader: (10)

Doubtful. The bumpstops would keep that from happening. Without knowing anything else about your car, it's damn near impossible to diagnose.

Could be the torque arm hitting the tunnel (if the rearend and torque arm are aftermarket), could be the exhaust hitting the upper panhard bar...could be any number of things.


-Mike

LowSS

Thanks for the replies, I'm going to take a closer look at it this weekend and i'll post what I find.